The invention relates generally to the field of navigational aid structures for blind and visually impaired (B/VI) persons. More particularly, the invention relates to environmentally-placed systems and devices for facilitating tactile navigation by B/VI persons within a structurally-varied environment.
Blind and visually impaired (B/VI) persons face substantial challenges navigating in complex environments, particularly in urban environments. This is largely due to the large number and variety of obstacles presented to them, and can be further complicated by the cacophony of noises which may be difficult to differentiate, locate, and identify. Examples of navigational obstacles include abrupt changes in the elevation of a walking surface (e.g., stairs, curbs, etc.), building entries, transit vehicle embarkation points (e.g., bus stops, train platforms, etc.), crosswalks, and others. Many types of obstacles are themselves a destination, and must be successfully located, navigated to, and transited in order to reach an intended destination.
Sighted persons can quickly and easily visually differentiate one type of obstacle from another, determine an approach direction to and distance from an obstacle, and successfully navigate throughout their physical environment relying almost solely on sight. For B/VI persons, however, tactile navigation is a critical method for self-guided navigation. Examples of tactile navigation include detecting surface mounted markers underfoot, feeling along elevated structures (e.g., walls, railings, etc.), or more commonly, using a cane or similar device to sweep an approach path and feel for the presence (and/or absence) of structural obstacles.
Numerous forms of tactile navigational aid structures and/or systems have been proposed and/or implemented. One example includes providing a plurality of raised bumps or linear segments arranged at a surface of a walking path, extending longitudinally along the path to continuously guide a B/VI person along the length of the path. As long as the person can feel the bumps underfoot, they know they are still approximately centered within the path. However, such linear pathway guides provide only a means and/or method to keep a person following a prescribed course, and generally do not provide information or guidance regarding surrounding obstacles, nor how to locate an entrance to the path in the first instance.
Another similar walking-surface-located guidance structure includes the commonly seen array of small domes, or ‘truncated’ domes, typically placed at or near an entry to a crosswalk. A B/VI person arriving at such an array can detect elevations (typically) present at the walking surface. However, the arrays are both overly complex, and insufficiently informative. The large number of individual bumps does not provide much information except to convey, for example, “You have arrived near an obstacle”. The B/VI person is left to discern the environment through various cues, such as listening for audible indications (e.g., presence of passing traffic, etc.) and/or searching for structural details in the environment to determine the nature of the obstacle, which direction to navigate, etc.
One concept, described in U.S. Pat. No. 6,964,244 ('244) entails a plurality of parallel, substantially identical longitudinally-elongated elevated structures forming a pattern. According to '244, a pattern can include, for example, two identical parallel structures disposed at a surface of a walking path to indicate one type of obstacle, and three identical parallel structures to indicate another type of obstacle.
Additionally, the '244 structures are typically arranged to longitudinally ‘point’ in a direction corresponding to a subsequent direction of travel so that a user will arrive at the obstacle so marked. While the '244 concept does differentiate some types of obstacles from others, and provide some amount of directional guidance, it does not solve all problems of the prior art.
First, although the described patterns provide some directional information, they equally and simultaneously direct B/VI persons both toward an obstacle as well as 180-degrees away from the obstacle. The patterns tell a person to either go left or right along a longitudinal direction of the pattern structures, for example, but include no further indicia of which direction is proper.
Secondly, each structure within a pattern is identical to each other structure in the pattern, all of which are simply longitudinally-elongated stripes. As a logical consequence, each tactually-detectable portion of each structure is exactly like each other portion of the structure, as well as of each other structure. Therefore, the structures provide no integral indicia of proximity to an obstacle, and in particular, no progressive indicator(s) of proximity as a person more closely approaches an obstacle. Any sweep of a pattern of structures reveals the same as each prior sweep, leaving the user again to search for and rely upon extrinsic environmental cues (e.g., structures, sounds, etc.) to determine proximity to an obstacle. The unfortunate reality not comprehended by '244 is that environmental cues are inconsistent throughout any environment in which a B/VI person attempts to navigate, and can vary at any single location from one particular time to another time (e.g., as objects are moved, types and volumes of sounds vary, etc.).
Further frustrating determination of proximity, beyond setting a minimum preferred length of the structure, '244 provides no link between any particular length of the structure and any relationship to surrounding structures. Rather, '244 requires (only) that the structure of a pattern be ‘substantially identical’.
Additionally, the '244 patterns are self-contained, including no indicia at a surrounding walking surface to guide a B/VI person to the pattern. The '244 patent entirely leaves detection of its patterns and guidance system to chance, and this omission in '244 is not accidental. Rather, '244 expressly and unambiguously requires that all areas of an underlying walking surface surrounding and extending from any of its described patterns remain entirely unaffected and unaltered by the guidance system. Of course, a person derives benefit from the '244 patterns only after first being able to encounter and detect them.
Thus, numerous navigational challenges presented to B/VI persons each day remain unaddressed by, and in substantial ways further complicated by, the prior art.